Filter and method of making same



Nov. 27, 1956 fm, GAARDER 2,772,195

FILTER AND METHOD OF MAKING SAME Filed April 8, 1952 United StatesPatent FILTER AND METHOD OF MAKING SAlVlE Herbert M. Gaarder, Chicago,Ill., assignor to Wilson & Co., Inc., a corporation of DelawareApplication April 8, 1952, Serial No. 281,209

14 Claims. (Cl. 154-101) This invention relates to filters and tomethods of making the same, particularly filters made from hair,especially short hairs or fibers. The filter of the present invention isparticularly adaptable for use as an air cleaner for automobiles.

In the past, hair filters have been made almost exclusively from longstaple, curled cattle tai-l hair. 7 This type of hair is relativelyexpensive and frequently in limited supply. Short hair, for example hoghair, horse tail and mane hair combings and the like, is relativelyinexpensive and plentiful. Prior to the present invention, loose,intermeshed filters such as air cleaning filters and the like, have notbeen formed successfully from short hair or fiber. The short hairs couldnot be uniformly distributed, and would also shed. When formed frombatts by methods hitherto attempted, open spaces would be presentbetween the layers of material, with resulting channeling and loss ofefficiency in filtering action. The filter of the present invention isuniform and substantially free from such voids or open texture areas andis consequently ver efiicient. The layers or spirals of hair are bondedto one another and the hairs in one layer are intermingled with thehairs of the adjacent layer. Employing the method of the presentinvention, filters may be made from short coarse hair or coarse fiberwhich has been initially formed into a batt of intermingled fibers inthe conventional manner. The batt is sprayed with a suitable adhesivepreferably a thermoplastic adhesive, and then cut into strips of desiredwidth and length. The strips are shaped into the desired form, forexample, by rolling into a coil or spiral, and the 'coil is then steamedto soften and relax the hair and also to soften the thermoplasticadhesive. After steaming, the shaped filter is dried and cooled, therebysetting it in its final form and setting the adhesive to a hardenedcondition.

By the present invention 1 am able to produce an inexpensive hair aircleaner which is easily and quickly fabricated. The hairs in the filterare uniformly distributed throughout the filter. There are no excessivevoids or open spaces between adjacent layers or within layers to causechanneling and ineffective filtration.

Other advantages or" the filter of the present invention and the methodof making same will be apparent upon examination of the followingspecification taken inconjunction with the accompanying drawings inwhich:

Figure l is a schematic representation in perspective of apparatussuitable for continuously spraying a batt of hair and cutting said battinto strips of desired width and length;

Fig. 2 is a perspective view of a strip of hair batt prior to its beingrolled into a filter-body;

Fig. 3 is a top plan view of a spirally coiled batt prior to finaltreatment;

Fig. 4 is a view similar to Fig. 3, showing the coiled batt orfilter-body in perspective;

Fig. 5 is a perspective view of a container or mold having a perforatedbottom, and into which the coiled batt or filter-body is placed incarrying out the present invention;

Fig. 6 is a side elevation of a conveyor system, schematically showingthe perforated containers or molds, which contain the filter-bodies,passing over treating means in accordance with the present invention;

ice

Fig. 7 is a top plan view of a plurality of molds positioned on theconveyor belt as shown in Fig; 6;

Fig. 8 is a perspective view of a coiled filter after it has beencompletely processed; and

Fig. 9 is a perspective view of a modified formof-l-arninated filter,showing the method of assembly.

The filter of the present invention is made from a batt of short hairsor fibers which has been preformed in a conventional manner. By short Imean hairsoffrom about one-half inch to five inches in length, the hairsemployed in the present invention ranging from aboutone to three inchesin length, generally in admixture.

The hairs employed may be either naturally curled, artificially curledorstra-ight. They may 'be coarse natural animal hair such as hog hair,cattle :tail hair, horse tail hair, and horse mane hair. Coarse naturalvegetable fibers such as tula, tampico, or coconut fibers, or coarsesynthetic fibers may also be used. Coarse hair and fibers are preferredbecause they do not have the tendency -to felt or mat as do fine hairand fibers, such as cattle body hair.

Referring to the drawings, in an illustrative example a batt of shorthairs 11, as hereinbefore described is sprayed with a thermoplasticadhesive, dried as by passing it through a conventional drying tunnel(not shown) and then cut into strips of desired length and width. Thespraying, drying and cutting maybe a continuous operation. As shown inFigure l, the batt 11 passes under a spray mechanism 12 attached to asuitable source of supply of athermoplastic adhesive (not shown) Afterpassing under the spray mechanism, batt 11 is passed through suitabledrying means (not shown) and is then cut into strips of desired width bymeans of cutter blades 13. The strips are cut into suitable lengths bycutter blade '14. The strip or ba-tt of desired width and length, cutfrom a larger batt by cutter blades 13 and 14, is shown in Fig.

2 identified by the numeral 15. I

Although both sides of the strip may be sprayed with adhesive ifdesired, it is preferred to spray but one side of batt 15. Spraying oneside only is found to be as effective as spraying both sides, and isquicker and cheaper and shortens the subsequent steaming operationdescribed below. It is preferred that the adhesive :be applied byspraying, but it may also be applied by dipping the batt in an adhesive.The adhesive may be applied in the form of a solution, dispersion or inthe molten state. An aqueous dispersion is preferred because of the easeof application and for safety reasons. 7

Any thermoplastic type of adhesive may be used. Thermoplastic syntheticresins such as polystyrene, polyvinyl chloride, polyvinyl acetate,polyvinyl chlorideacetate, polyethylene, etc. may be used. Where waterresistance is not a factor, water soluble adhesives such as gum arabic,vegetable glues, animal glues, fish glues, casein or other proteinadhesives may be also employed. The adhesive used should be capable ofsoftening under the influence of steam and/or heat and it is preferableto use an adhesive which softens completely around C.

The adhesive aids in binding together the hairs in the batt or strip 15and likewise serves to cause adjacent layers of the batt 15, when coiledor laminated, to become bonded together. It also serves to aid inintermingling and thus securing the hairs of one layer with the hairs ofan adjacent layer.

After batt 15 has been sprayed with adhesive, as shown in Figs. 3 and 4it may be rolled into a coil or spiral 16, jelly roll fashion. Thelayers of the coil are designated by numeral 21. Even if the strip orbatt had been sprayed only on one side, when coiled the sprayed sidewill always be in contact with the unsprayed side, thus assuring thepresence of the adhesive between the coils or layers, It

will be noted that, in the form illustrated, a central axial aperture 17is left in the coil. Most automobile air fil-ters have such an aperture;however, if the item is to be made for a different purpose, the coil maybe Wound into a solid cylinder. Coil 16, which constitutes afilter-body, is wound so that its outside diameter is no smaller than,and preferably is slightly greater than the inside diameter of acontainer or mold 18. The coil or filter-body 16 is then squeezed .ortucked into mold 18 before being subjected tofurther treatment, mold 18serving to hold the filterbody in shape-during such further treatment.If filterbody 16 is provided with a central aperture 17, mold 18 isprovidedwith an internal cylindrical tube 19 to aid in maintaining theproper shape of the filter-body.

It-will be noted that at this juncture in my method, layers 21- of-thefilter-body are not bonded to one another.

, There, are frequently voids or open spaces, indicated in anexaggeratedway at 22 in Figs. 3 and 4, between adjacent layers 21. If these voidsare not closed, the filter will channel and be inefficient. The furthersteps of my method serve to close such voids and causethe coil to bebonded into a homogeneous unit in which the hairs are uniformly andintimately dispersed throughout the entire .(although it may be ascoarse as 2 mesh), or a perforated plate. If a perforated plate is used,the perforations may suitably be from one-eighth to one-half inch indiameter, and at least 50% of the entire area of the bottom shouldbeperforated.

. Moldsl8 having filter-bodies 16 positioned therein, are placed onanarrow conveyor belt 24, as shown in Figs. 6 and 7'. The-conveyor beltis of conventional linked plate construction and is provided with anopening 24a in each plate,-of a shape corresponding to the shape of themold but ,of a somewhat smaller size so that themold may be supported onthe belt over the opening, as shown. The mold may'also be made with adownwardly depending flange to securely hold it in opening 24a, or themold may fit into theopening in any other suitable manner. The conveyorbelt carrying the molds 18 travels in the direction indicated by thearrow in Fig. 6.

In their travel, the filter-bodies in the molds are successivelysubjected to treatment with steam, hot air and cold air which passthrough openings 24a, through the perforated bottoms of the molds andthrough filter-bodies '16. -For this-purpose, a sequence of treatingmeans may be provided below the conveyor belt 24. As shown in Fig. 6,these treating means are diagrammatically illustrated as three sets ofchambers 25, 26 and 27. Chamber 25 is connected by connection 25a to asource of stem;

- chamber 26 is connected by connection 26a to a hot air supply,andcharnber 27 is connected by connection 27a. to a cold air supply. Asthe filter-bodies in the molds pass over steam chamber 25, steam passesupwardly through the perforated bottoms 23 of molds 18 and copiouslysteams the filter-bodies 16. The moisture and heat in the steamingstepsoften the adhesive and the hairs and cause the hairs to shiftposition whereby the denser areas open up and; fill adjacent voidslorareas which are less dense, therebysecuring a'greater uniformity anddistribution of the; hair. 'After the filter-bodies have beensteamed,.they pass over hot air chamber 26 or other suitable heatingmeans, which dries the steamed filter-bodies 16. The dried filter-bodiesare then cooled by passing them over chamber 27, which supplies cold airto cool the .filterbodies 16 and set the resin or adhesive. After beingso treated, the layers of the filter-body are bonded together, anyunduly large voids or open areas between or within the layers aredissipated and, the filter-body has been transformed into a completedfilter 28 (Fig. 8).

v The steam bath serves to soften the thermoplastic adhesive and alsosoftens and relaxes the hair. This action,

a a particularly when the filter-body is confined in the molds 18,causes the hairs of adjacent layers 21 to intermingle with one anotherand the thermoplastic adhesive aids in maintaining such intermingling;After the filter-body has been steamed, the hot air blast serves to dryand restore the hairs to their natural unsoftenedcondition. Thesubsequent cold air blast serves to cool thecoil and set thethermoplastic adhesive. The coil may be cooled merely The filter 28,which is removed from mold 18 after the mold has been cooled, issubstantially uniform in texture and in distribution of the hair. Voidsor open areas 22 which existed in the filter-body before final treatmentno longer exist, the hairs being completely intermingled and bonded bythe thermoplastic adhesive at the points where voids 22 originallyexisted. Normally, the hairs on the outside surfaces of'filter 28, whenformed as herein described will not shed, but to'obviate any possiblesheddingv of the hairs, filter 28 may be sprayed lightly with anysuitable adhesive'binder.

In Fig. 9 there is shown a modified form'offilter. This filter is madeby punching disks or pads 29 from a batt suchas batt 11 after the batthas been sprayedwith a thermoplastic adhesive. The disks may be providedwith an aperture 30 if desired. Afterthe disks have been punched fromthe batt, they are stacked one on top of another, as indicated inFig. 9.If batt 11 was sprayed only on one side, disks 29' are stacked so thateach. adjacent pair of disks has a layer of adhesive therebetween;

The disks are then placed in a mold 18 and together coneach disk issecurely bonded to each adjacent disk by the thermoplastic adhesive.

The filters of the presentinventi-on may vary in density I from aboutbetween 0.4 gram per cubic inch to about 0.8 gram per cubic inch. Adensity between 0.5 gram and 0.7 gram per cubic inch is preferred. 7

I have described, in considerable detail, my novel'hair filter togetherwith the method. of making same but it is to be understood that thedescription herein contained is intended to be illustrative rather thanrestrictive as modifications may be made without departing from thespirit or scope of the invention. For example, it isnot necessary thatthe filters of the present invention be made cylindrical, but, any shapewhich is desired may. be produced Whether it be made from a coil or froma plurality of laminae. Accordin ly, i do'not intend to be restricted bythe details of the examples ofthe invention herein set forth except inso far as contained in the accompanying claims.

I claim: I

1. The method of forming a hair filter of substantially uniform texturefrom short hairs comprising the steps of forming the hairs into layers,placing such layers in juxtaposition to form a filter-body, providingthermoplastic adhesive between the juxtaposed layers, steaming thefilter-body to soften the hair and adhesive and to secure uniformity ofdistribution of. the hairs, and drying and cooling the filter-body toset the adhesive and bond the within said mold to soften the hair andadhesive and to secure uniformity of distribution of the hairs, anddrying and cooling the filter-body within the mold, thereby bonding theadjacent layers and setting and giving final form to the filter.

3. The method of making a hair filter of substantially uniform texturefrom short hairs comprising the steps of forming the hairs into a batt,spraying only a surface of said batt with a thermoplastic adhesive,winding said sprayed batt into a coil, said coil being so wound thatsaid sprayed surface of each layer or turn is in contact with theunsprayed surface of the adjacent layer or turn, steaming said coil,thereby softening and relaxing the hair and softening the adhesive,drying said coil, and then cooling said coil, thereby setting the a l.esive and bondin the adjacent layers of said coil to one another.

4. The method of making a hair filter of substantially uniform texturefrom short hairs comprising the steps of forming the hairs into a batt,spraying only the surface of said batt with a thermoplastic adhesive,winding said sprayed batt into a coil so that said adhesive ispositioned between adjacent layers of said coil, moistening said coil,heating said coll, thereby softening and relaxing the hair and softeningthe adhesive, and then cooling said coil to set the adhesive and bondthe adjacent layers of said batt to one another.

5. The method of making a hair filter of substantially uniform texturefrom a batt of short hairs comprising the steps of spraying a side ofsaid batt with a thermoplastic adhesive, winding said sprayed batt intoa coil so that said adhesive is positioned between adjacent layers ofsaid coil, placing said coil in a mold, said mold having openings foradmission of steam, and then steaming, drying and cooling said coilwhile it is in said mold to first soften and relax the hairs and causethe hairs of adjacent layers of said coil to intermingle and then to setthe adhesive to bond said adjacent layers together.

6. The method of making a hair filter of substantially uniform texturefrom a batt of short hairs comprising the steps of spraying at least oneside of said batt with a thermoplastic adhesive, punching said batt intoa plurality of formed layers, stacking said layers alignment on top ofone another with adhesive between the adjacent layers, thereby forming afilter-body, steaming the filter-body to soften the hair and adhesiveand to secure uniformity of distribution of the hair, and drying andcooling the filterbody, thereby setting the filter and bonding theadjacent layers to one another.

7. The method of making a hair filter of substantially un form texturefrom a batt of short hairs, comprising the steps of spraying at leastone side of said batt with a thermoplastic adhesive, punching said battinto a plurality of formed layers, placing said layers on top of oneanother with adhesive therebetween to form a laminated filter-body,placing the filter-body in a confining mold provided with openings forthe admission of steam, steaming the filter-body Within said mold tosoften the hair and adhesive and to secure uniformity of distribution ofthe hairs, and drying and cooling the filter-body within the mold,thereby setting and giving final form to the filter and bonding theadjacent layers to one another.

3. The method of forming a fiber filter of substantially uniform texturefrom short fibers comprising the steps of forming the fibers intolayers, placing such layers in juxtaposition to form a filter-body,providing thermoplastic adhesive between the juxtaposed layers, steamingthe filterbody to soften the fiber and adhesive and to secure uniformityof distribution of the fibers, and drying and cooling the filter-body toset the adhesive and bond the adjacent layers of said batt to oneanother.

9. The method of forming a fiber filter of substantially uniform texturefrom short fibers which comprises the steps of forming the fibers intolayers, placing such layers in juxtaposition to form a filter-body,providing thermoplastic adhesive between the juxtaposed layers, placingthe filter-body in a confining mold provided with openings for theadmission of steam, steaming the filter-body within said mold to softenthe fiber and adhesive and to secure uniformity of distribution of thefibers, and dlying and cooling the filter-body Within the mold, therebybonding the adjacent layers and setting and giving final form to thefilter.

10. The method of making a fiber filter of substantially uniform texturefrom short fibers comprising the steps of forming the fibers into abatt, spraying only a surface of said batt with a thermoplasticadhesive, winding said sprayed batt into a coil, said coil being sowound that said sprayed surface of each layer or turn is in contact withthe unsprayed surface of the adjacent layer or turn, steaming said coil,thereby softening and relaxing the fiber and softening the adhesive,drying said coil, and then cooling said coil, thereby setting theadhesive and bond ing the adjacent layers of said coil to one another.

11. The method of making a fiber filter of substantially uniform texturefrom short fibers comprising the steps of forming the fibers into abatt, spraying only the surface of said batt with a thermoplasticadhesive, winding said sprayed batt into a coil so that said adhesive ispositioned between adjacent layers of said coil, moistening said coil,heating said coil, thereby softening and relaxing the fiber andsoftening the adhesive, and then cooling said coil to set the adhesiveand bond the adjacent layers of said batt to one another.

12. The method of making a fiber filter of substantially uniform texturefrom a batt of short fibers comprising the steps of spraying a side ofsaid batt with a thermoplastic adhesive, Winding said sprayed batt intoa coil so that said adhesive is positioned between adjacent layers ofsaid coil, placing said coil in a mold, said mold having openings foradmission of steam, and then steaming, drying and cooling said coilwhile it is in said mold to first soften and relax the fibers and causethe fibers of adjacent layers of said coil to intermingle and then toset the adhesive to bond said adjacent layers together.

13. The method of making a fiber filter of substantially uniform texturefrom a batt of short fibers comprising the steps of spraying at leastone side of said batt with a thermoplastic adhesive, punching said battinto a plurality of formed layers, stacking said layers in alignment ontop of one another with adhesive between the adjacent layers, therebyforming a filter-body, steaming the filter-body to soften the fiber andadhesive and to secure uniformity of distribution of the fiber, anddrying and cooling the filter-body, thereby setting the filter andbonding the adjacent layers to one another.

14. The method of making a fiber filter of substantially uniform texturefrom a batt of short fibers, comprising the steps of spraying at leastone side of said batt with a thermoplastic adhesive, punching said battinto a plurality of formed layers, placing said layers on top of oneanother with adhesive therebetween to form a laminated filter-body,placing the filter-body in a confining mold provided with openings forthe admission of steam, steaming the filter-body Within said mold tosoften the fiber and adhesive and to secure uniformity of distributionof the fibers, and drying and cooling the filter-body Within the mold,thereby setting and giving final form to the filter and bonding theadjacent layers to one another.

References Cited in the file of this patent UNITED STATES PATENTS1,898,027 Winslow Feb. 21, 1933 2,426,405 McDermott Aug. 26, 19472,464,301 Francis Mar. 15, 1949 2,476,282 Castellan July 19, 19492,543,101 Francis Feb. 27, 1951 2,546,230 Modigliani Mar. 27, 19512,579,984 Trowbridge Dec. 25, 1951 2,582,915 Sebok Jan. 15, 19522,660,166 Coleman Nov. 24, 1953

1. THE METHOD OF FORMING A HAIR FILTER OF SUBSTANTIALLY UNIFORM TEXTUREFROM SHORT HAIRS COMPRISING THE STEPS OF FORMING THE HAIRS INTO LAYERS,PLACING SUCH LAYERS IN JUXTAPOSITION TO FORM A FILTER-BODY, PROVIDINGTHERMOPLASTIC ADHESIVE BETWEEN THE JUXTPOSED LAYERS, STEAMING THE